Bioabsorbable breast implant

ABSTRACT

A breast implant has at least an outer shell which is composed of a resorbable material. The implant, which can be formed entirely of bioresorbable material such as a collagen foam, is sized and shaped to replace excised tissue. The implant supports surrounding tissue upon implantation, while allowing for in-growth of fibrous tissue to replace the implant. According to various alternative embodiments, the implant is elastically compressible, or can be formed from self-expanding foam or sponges, and can be implanted through a cannula or by injection, as well as by open procedures. The implant can carry therapeutic and diagnostic substances.

[0001] This application is a continuation-in-part of U.S. patentapplication Ser. No. 09/169,351 filed Oct. 9, 1998, which claimed thebenefit of U.S. Provisional Application Serial No. 60/061,588, filedOct. 10, 1997, U.S. Provisional Application Serial No. 60/077,639, filedMar. 11, 1998, and U.S. Provisional Application Serial No. 60/091,306,filed Jun. 30, 1998, the disclosures of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to implantable prostheses. Moreparticularly, the present invention relates to implantable breastprostheses designed to eliminate encapsulation and reduce scarring, andto replace tissue removed for purposes of biopsy or lumpectomy.

[0004] 2. Description of the Related Art

[0005] Breast prostheses are utilized for augmentation mammoplasty andin cosmetic surgery. Prostheses also are indicated in breast cancersurgery, such as lumpectomies, where a portion of the breast is removedand can leave some disfigurement if not replaced by a similar amount oftissue and/or augmentation material.

[0006] Similarly, biopsies can leave small dimples or imperfections ifremedial steps are not taken. About 1 million breast biopsies areperformed in the United States annually. As a result, some 200,000 newbreast cancers are diagnosed each year.

[0007] Known methods of augmentation mammoplasty utilize silicone orsaline implants. These methods have been complicated post-operatively byencapsulation of the implants, which can occur to varying degrees.Encapsulation produces a hard area of scar tissue around the implant,resulting in a rigid, abnormally-shaped mound beneath the breast tissueor pectoralis muscle, depending upon the placement of the implant.

[0008] Moreover, the known implant materials may not be indicated forreplacement of smaller amounts of tissue, as would be required toprevent dimpling after biopsies, for example. Further, the known implantmaterials are not amenable to resizing. In addition, known implants arenot capable of being implanted through a cannula or needle, and are notreadily instilled with medicaments or chemical agents that would beuseful in treating the patient.

[0009] Accordingly, a need exists for implants and methods that can beadapted for replacement of small as well as large amounts of tissue. Aneed also exists for implants that can be delivered through cannulae orneedles, as well as being able to significantly reduce or eliminateencapsulation, resulting in a prolonged, aesthetically pleasing, softmound below the breast tissue or pectoralis muscle. In addition, a needexists for implants into which useful substances, such as beneficialmedications, chemical agents, hormonal treatments, stem cells, such asadipocytes, cellular precursors and components, and radiation media canbe instilled to enhance the treatment capabilities of the implant incancer and other breast pathology.

SUMMARY OF THE INVENTION

[0010] The present invention overcomes deficiencies of the prior art,such as those noted above, by providing an implant in which at least theouter portion of the implant, and as much as the entire implant, is madeof a resorbable material. The implant is sized and shaped to replaceexcised tissue. Preferably, the implant provides a support structure inthe form of a framework or scaffold for the surrounding tissue afterimplantation. The support structure preferably is porous to permit thein-growth of fibrous replacement tissue. Advantageously, replacementtissue in-growth takes place without encapsulation and with reducedscarring.

[0011] According to an embodiment of the invention, excised tissue isreplaced by installing an implant having at least an outer shell ofresorbable material. The implant is sized and shaped to replace theexcised tissue. The implant supports surrounding tissue while fibroustissue replaces the resorbable portion of the implant.

[0012] In a further development, at least a portion of the implant canbe provided in the form of a compressible or non-compressible sponge orfoam, or a self-expanding sponge or foam. The sponge or foam provides aporous support matrix for surrounding and in-growing tissue. In the formof a compressible, expandable, or self-expanding sponge or foam, theimplant advantageously can be inserted through a cannula or a needle, oroptionally can be directly inserted. Additionally, the implant can beinstilled with beneficial materials, such as indicated medicaments,therapeutics, or diagnostic agents, as well as matrix enhancingadditives.

[0013] Other features and advantages of the present invention willbecome apparent from the following description of the invention whichrefers to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1 is a schematic elevation of a breast implant according to apreferred embodiment of the present invention.

[0015]FIG. 2 is a schematic sectional view of a breast afterimplantation of the implant of FIG. 1.

[0016]FIG. 3 is a schematic sectional view of a breast afterimplantation of an alternative embodiment of the implant of the presentinvention.

[0017]FIG. 4 is a schematic sectional view of a breast implant accordingto a second alternative embodiment of the present invention.

[0018]FIG. 5 is a schematic sectional view of a breast afterimplantation of the implant of FIG. 4.

[0019]FIG. 6 is a schematic sectional view of a breast implant and amethod of insertion according to further alternative embodiments of thepresent invention, particularly for cases involving the removal ofsmaller pieces of tissue such as by biopsy and lumpectomy.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Referring initially to FIGS. 1 and 2, an implant 2 has an outershell 4 made of a biosorbable material woven into a mesh. The innercontents of the implant are fluids such as saline and autologous bloodproducts.

[0021] Outer shell 4 is made entirely of biosorbable materials, such ascollagens or polyglycolic acids, for example. Over a period ofapproximately three weeks to six months, the outer shell dissolves,leaving the inner contents 6 present inside the breast. Hardencapsulation will not occur because there is not a foreign bodycontained within the prosthetic space.

[0022] Referring to FIG. 3, implantation of an alternative embodiment ofimplant 2 is illustrated in which the outer shell 4 includes bothbiosorbable material, and non-absorbable material, such as monofilamentpolypropylene fibers. Outer shell 4 is provided as a mesh or weave ofthe mixed material, surrounding contents 6 as described above. After aresorption period, contents 6 remain surrounded by a skeletal outershell made up of non-absorbable fibers 8.

[0023] Advantageously, the proportions and spacing of the two types ofmaterials can be altered to provide the desired properties ofcontainment using a minimal amount of nonabsorbable material.Accordingly, the non-absorbable fibers 8 which remain after thebiosorbable materials resorb will act as a scaffolding to allow theprosthesis to hold its shape; however, because of the limited amount offoreign material, encapsulation and scarring are decreased.

[0024] Referring to FIGS. 4 and 5, a second alternative embodiment ofthe present invention is shown. A prothesis 10 features two capsules, alarger, outer capsule 12 made of biosorbable materials, and a smallerinner capsule 14 made of a non-absorbable material. Inner capsule 14also can be made partially resorbable as in the first alternativeembodiment above. Outer capsule 12 and inner capsule 14 can be separatedby a thin layer 16 of saline or autologous fluids such as thosedescribed above. Inner capsule 14 surrounds a more permanent prosthesis18 made of autologous fluids or saline, for example.

[0025] After implantation, outer capsule 12 dissolves, thus preventinghardening by encapsulation of the prosthesis. The supply of fluid 16between the capsules (a few to several cc.'s) is absorbed by the bodyonce released by the dissolution of outer capsule 12.

[0026] Referring to FIG. 6, a further alternative embodiment of thepresent invention includes an implant prosthesis 20 provided in the formof a matrix framework, such as a sponge or foam. The implant, whichpreferably is entirely biodegradable (resorbable), has a porousstructure which supports the surrounding tissue and provides a frameworkfor the in-growth of fibrous tissue material.

[0027] According to a preferred embodiment, the implant is provided inthe form of a foam or sponge which can be modified by a surgeon prior toimplantation, such as at a lumpectomy or biopsy site, simply by trimmingthe sponge to the appropriate size and shape. Alternatively, the implantcan be a pre-shaped prosthesis of appropriate size, or an appropriateamount of foam or foam-forming materials. Optionally, the foam can beprovided as a self-expanding matrix that either is compressed, or formsin situ. Advantageously, the implant can be modified to correspond tothe breast tissue that either has been removed, requires replacement, orrequires augmentation. The foam or sponge matrix is sufficientlyresilient to support the surrounding tissue without collapsing.

[0028] A preferred method of implantation is illustrated schematicallyin FIG. 6, whereby the implant is elastically compressible, and isdelivered using a cannula or needle 22 inserted into the breast. Asingle implant 20 is shown being compressed so as to fit within cannula22. A force is applied to drive the compressed implant distally throughand out the distal end of the cannula into the implant site, where theresilient implant 20 expands to fill the implant site space.

[0029] The force for advancing the sponge or foam material through thecannula can be applied directly to the implant, or indirectly usingfluids, for example. Advantageously, the implant can be used inconjunction with stereotactic biopsy instrumentation, such as the ABBI®System, the MIB System by US Surgical, or the Mammotome® System byJohnson and Johnson.

[0030] As a further alternative, the sponge or foam implant of thepresent invention can form all or part of a larger implant, such asthose described above. Accordingly, the tissue supporting sponge or foammatrix will form, for example, all or part of the outer shell 4 ofimplant 2. Implantation using open procedures usually would be indicatedwhen the sponge implant of the present invention is used as all or partof a larger implant. Accordingly, the sponge or implant would be placeddirectly into the biopsy or lumpectomy cavity.

[0031] In addition, the implant 20 can be provided in the form of aself-expanding foam, which can be injected by needle or through cannula22 in a metered amount. An appropriate amount of foam-forming materialscan be inserted through cannula 22 and allowed to expand or form amatrix within the cavity created by the excised tissue. Alternatively, aspecialized applicator may be used to inject the desired amount of thefoam. The amount of foam is preselected to allow sufficient expansion tofill the void left by the excision and support the surrounding tissue toprevent dimpling.

[0032] Following insertion of the implant, such as by an open method orone of the stereotactic methods described above, the resorbable implantoccupies the breast tissue cavity and supports the surrounding tissueuntil such time as it resorbs or biodegrades. After initialimplantation, the patient's own fluids, fibroblast, and stem cells, suchas adipocytes, vascular stem cells, and others, permeate the spongeprosthesis. In the case of a small implant, such permeation would occurnaturally, subsequent to implantation. In the case of a larger implant,providing the implant at least partially filled with fluids prior toimplantation may be indicated.

[0033] Advantageously, the new prosthesis decreases encapsulation afterimplantation. Various biosorbable materials can be used in the implantof the present invention. Known biosorbable materials includepolyglycolic acid (Dexon, Davis & Geck); polyglactin material (Vicryl,Ethicon); poliglecaprone (Monocryl, Ethicon); and synthetic absorbablelactomer 9-1 (Polysorb, United States Surgical Corporation).

[0034] Other foamable materials that can be utilized in the presentinvention include, without limitation, proteins such as collagen,fibronectin, laminin and fibrin, most preferably collagen, and highmolecular weight polysaccharides, such as heparan sulphate, chondroitinsulphate, hylauronic acid and dermatan sulphate. Mixtures of any of theaforementioned materials also can be used, as required.

[0035] The materials can be modified, by cross-linking for example, tocontrol degradation rates over varying lengths of time, after which theyare substantially or completely resorbed.

[0036] Foams can be formed by various means known to those skilled inthe art, including injecting an aerosol into a gel, and freeze-dryingaqueous dispersions of the foam-forming material. Foaming agents can beincluded to promote formation of the foam. In addition, stabilizingagents can be included to enhance foam stability. The foams can beextruded or formed in situ.

[0037] According to the present invention, these products may be mixedwith one another or combined to provide various resorption times orgradients, and/or may be interrelated with non-absorbable materials,such as polypropylene or PTFE (Gortex) material, for example. In aninstance where a non-absorbable material is utilized, the non-resorbableimplant section will remain partially intact as a permanent structure.

[0038] In each of the embodiments, the resorbable portions of theprosthesis ultimately biodegrades, and the patient is left withautologous tissue, some of which may have been implanted, or a permanentimplant such as saline, as a filler for the biopsy cavity, thuspreserving the contour of the breast and preventing indentation of theoverlying skin.

[0039] The implants of the present invention further can be instilled,before or after implantation, with indicated medicines and otherchemical or diagnostic agents. Examples of such agents include, but arenot limited to, antibiotics, chemotherapies, other cancer therapies,brachytherapeutic material for local radiation effect, x-ray opaque ormetallic material for identification of the area, hemostatic materialfor control of bleeding, growth factor hormones, immune system factors,gene therapies, biochemical indicators or vectors, and other types oftherapeutic or diagnostic materials which may enhance the treatment ofthe patient.

[0040] The present invention has been described particularly inconnection with a breast implant, but it will be obvious to those ofskill in the art that the invention can have application to other partsof the body, such as the face, and generally to other soft tissue orbone. Accordingly, the invention is applicable to replacing missing ordamaged soft tissue, structural tissue or bone, or for cosmetic tissueor bone replacement.

[0041] Although the present invention has been described in relation toparticular embodiments thereof, many other variations and modificationsand other uses will become apparent to those skilled in the art. It ispreferred, therefore, that the present invention be limited not by thespecific disclosure herein, but only by the appended claims.

What is claimed is:
 1. An implant for implantation in a human bodycomprising an outer shell of a resorbable matrix material and an innerfluid core, the implant being formed to fit the shape and size of acavity in the human body, the implant being installed for supportingtissue surrounding the cavity and allowing in-growth of fibrous tissueinto and replacing the outer shell.
 2. The implant of claim 1 , whereinthe inner fluid core is resorbable.
 3. The implant of claim 2 , whereinthe core is filled with autologous material.
 4. The implant of claim 1 ,wherein the resorbable matrix material is elastically compressible. 5.The implant of claim 1 , wherein the resorbable matrix material isformed from one of a self-expanding foam, a compressible foam or sponge,and a non-compressible foam or sponge.
 6. The implant of claim 1 ,wherein the outer shell further comprises a non-resorbable material. 7.The implant of claim 1 , wherein the outer shell is formed of a foamedbioabsorbable protein.
 8. The implant of claim 1 , wherein the outershell is formed of a foamed collagen.
 9. The implant of claim 1 ,further comprising at least one medicinal, therapeutic, or diagnosticsubstance.
 10. The implant of claim 9 , wherein the at least onesubstance is selected from the group consisting of radiation materials,antibiotics, chemotherapeutics, cancer therapeutics, hemostaticmaterials, hormone therapeutics, and radiographic markers.
 11. Theimplant of claim 1 , wherein the core includes a saline solution. 12.The implant of claim 1 , further comprising a resorbable inner shellsurrounding the inner core, and a supply of fluid disposed between theinner shell and the outer shell.
 13. The implant of claim 1 , whereinthe outer shell is adjacent the inner core.
 14. The implant of claim 1 ,wherein the outer shell completely surrounds the inner core.
 15. Animplant for implantation in a human body comprising an outer shell of aresorbable material comprising collagen, the implant being formed to fitthe shape and size of a cavity in the human body, the implant supportingtissue surrounding the cavity upon implantation and allowing forin-growth of fibrous tissue into and replacing the outer shell, and aresorbable core provided inside and surrounded by the outer shell andcontaining autologous material.
 16. The implant of claim 15 , whereinthe core is partially enclosed by a nonabsorbable material.
 17. A breastimplant comprising a matrix of collagen material, the matrix having aporous structure for supporting surrounding tissue of a breast andconfigured to provide a framework for the in-growth of fibrous tissueinto the matrix.
 18. The breast implant of claim 17 , wherein the matrixcomprises a foam.
 19. The breast implant of claim 17 , wherein thematrix comprises a resilient framework for implantation by compressingthe matrix into a smaller volume, the matrix expanding resilientlywithin the breast.
 20. The breast implant of claim 17 , wherein thematrix is self-expanding.
 21. A method for replacing excised humanbreast tissue with an implant comprising the steps of: forming a cavityhaving surrounding tissue within a breast; forming the implant entirelyof resorbable material comprising collagen and sizing the implant tooccupy the cavity; and implanting the implant in the cavity, the implantsupporting the surrounding tissue and allowing for in-growth of fibroustissue into and replacing the resorbable material, wherein theresorbable material is elastically compressible, and the step ofimplanting includes the step of compressing the resorbable material. 22.The method of claim 21 , further comprising the step of introducing intothe implant at least one of a medicinal, therapeutic or diagnosticsubstance.
 23. The method of claim 21 , wherein the at least onesubstance is selected from the group consisting of radiation material,antibiotics, chemotherapies, cancer therapies, hemostatic material,hormone therapies, stem cells, cellular precursors, and radiographicmarkers.
 24. The method of claim 21 , wherein the step of implanting theimplant in the cavity comprises expanding the implant within the cavity.25. A method for replacing excised human breast tissue with an implantcomprising the steps of: forming a cavity having surrounding tissuewithin a breast; forming an implant entirely of resorbable material andsizing the implant to occupy the cavity; and implanting the implant inthe cavity, the implant supporting the surrounding tissue and allowingfor in-growth of fibrous tissue into and replacing the resorbablematerial, wherein the resorbable material is formed from aself-expanding foam and the step of implanting is performed by injectionof the self-expanding foam.
 26. The method of claim 25 , furthercomprising the step of introducing into the implant at least one of amedicinal, therapeutic or diagnostic substance.
 27. The method of claim26 , wherein the at least one substance is selected from the groupconsisting of radiation material, antibiotics, chemotherapies, cancertherapies, hemostatic material, hormone therapies, stem cells, cellularprecursors, and radiographic markers.